Synthesis, crystal structure and magnetic properties of zinc(II)-hexafluoro-acetylacetonate complexes with pyridyl-substituted nitronyl and imino nitroxide radicals

The reactions of zinc hexafluoroacetylacetonate (hfac) hydrate with pyridyl-substituted imidazolin-1-oxyl 3-oxide radicals in n-heptane obtained three new complexes, [Zn(hfac)2(NIT-mPy)2] (1) (NIT-mPy=2-(3-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxy 3-oxide), [Zn(hfac)2(NIT-pPy)2]2 (2) (NIT-pPy=2-(4-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxy 3-oxide), and [Zn(hfac)2(IM-oPy)] (3) (IM-oPy=2(2-pyridyl)-4,4,5,5,-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxy). Crystal structures and magnetic properties have been studied. In complexes 1 and 2, each zinc ion is six-coordinated with four oxygen atoms from two hfac ligands and two nitrogen atoms of pyridyl groups. In 3, each zinc ion is coordinated with a bidentate imino nitroxide and two hfac ligands. EPR and magnetic susceptibility data support that between the radicals in complexes 1–3 are intra- and intermolecular antiferromagnetic interactions. The magnetic behaviors are discussed in connection with the crystal structure.